BepiColombo Mercury mission bids farewell to Earth
BepiColombo, the joint European-Japanese mission to Mercury, has swung past the Earth - a key milestone in its seven-year journey to reach the "iron planet."
The gravitational flyby enabled the two-in-one space probe to bend a path towards the inner Solar System and bleed off some speed.
The mission needs to make sure it isn't travelling too fast when it arrives at Mercury in 2025 or it won't be able to go into orbit around the diminutive world.
"It would be so nice if we could take an express transfer and then we'd be there in a few months, but that doesn't work for this mission," Elsa Montagnon, the flight controller in charge of BepiColombo at the European Space Agency (Esa), told BBC News.
As well as this flyby of Earth, Bepi must perform two similar manoeuvres at Venus and six at Mercury itself to get itself into position..
The only alternative would have been to give the spacecraft a colossal volume of fuel to use in a braking engine. An impractical solution.
Bepi came within 13,000km (8,000 miles) of the Earth's surface. Closest approach was at about 05:25 BST (06:25 CEST).